[bindings] Pass v8::Local<v8::Value> by value in NativeValueTraits<T>::nativeValue()

Source/bindings/templates/union.cpp

Index: Source/bindings/templates/union.cpp
diff --git a/Source/bindings/templates/union.cpp b/Source/bindings/templates/union.cpp
index 53670a68e20db44aedb0d08c3a6dbbd1a2c07e6d..73c466f0f45d814eb9ac56aa3206aca75b403a5e 100644
--- a/Source/bindings/templates/union.cpp
+++ b/Source/bindings/templates/union.cpp
@@ -184,7 +184,7 @@ v8::Local<v8::Value> toV8(const {{container.cpp_class}}& impl, v8::Local<v8::Obj
     return v8::Local<v8::Value>();
 }
 
-{{container.cpp_class}} NativeValueTraits<{{container.cpp_class}}>::nativeValue(const v8::Local<v8::Value>& value, v8::Isolate* isolate, ExceptionState& exceptionState)
+{{container.cpp_class}} NativeValueTraits<{{container.cpp_class}}>::nativeValue(v8::Local<v8::Value> value, v8::Isolate* isolate, ExceptionState& exceptionState)
 {
     {{container.cpp_class}} impl;
     V8{{container.cpp_class}}::toImpl(isolate, value, impl, exceptionState);